The present invention relates to a laser head in a laser beam processing machine having a housing, in the interior of which a beam chamber is arranged and at the end of which a nozzle is arranged for the exit of the laser beam and a working gas.
Laser heads are widely known and are also referred to as welding heads, especially in the context of laser welding. In principle, however, such laser heads are used not only for welding but also to cut materials.
The laser heads (welding heads) comprise in principle a concave mirror or a lens, which focuses the laser radiation. The converging beam is guided through a beam chamber inside a housing, which is closed by a nozzle. The beam emerges through this nozzle and is focused onto the processing site. The known laser heads generally also have additional bores through which a working gas is either introduced coaxially into the beam chamber or fed via additional bores through a separate nozzle from the outside of the laser head.
When the settings of the laser head are changed, for example because of different materials or material thicknesses, for the purpose of focusing it is necessary on the one hand to adjust the optics, but on the other hand the nozzle also needs to be changed. Furthermore, contamination of the very fine nozzle can also readily take place during processing due to material splashes, so that a nozzle change is also necessary for this reason.
So that it is still possible to aim through the narrow nozzle with changed settings, and not have to change the nozzle, in various devices the focusing lenses are shifted horizontally. This, however, produces errors in the focusing because the lens is no longer illuminated centrally. The focus is therefore not optimal, which leads to inferior cutting results in laser cutting. Off-center illumination furthermore leads to stresses in the lens, so that the heat distribution and therefore the refractive index changes differently at the edges of the lens. This in turn leads to a further deterioration of the focus.
JP 64 07 1590 in this regard discloses the use of a lens disk, which comprises a plurality of lenses that can be rotated about an axis so as to be rotatable into the beam path. Although it is possible to change the lenses very quickly in this way, it is nevertheless necessary as before to fit the most expedient nozzle for the respective application.
In practice, therefore, the nozzle is unscrewed manually and a new nozzle is fastened on the housing of the welding head. This takes a relatively long time and interferes with the automatic process.
JP 62 25 4993 discloses an automatic nozzle changer which comprises a nozzle magazine. This nozzle magazine has the shape of a vertically arranged disk and a multiplicity of nozzles arranged on it. The nozzle required for the next processing step is selected on the disk by rotating the magazine, and replaced by a changer arm.
JP 06 02 3580 describes a similar device for replacing nozzles, in which the laser head moves by X-Y movement to a nozzle changer part which carries a multiplicity of different nozzles and rotates.
JP 200-126888 A discloses various configurations of alternating nozzles. In one configuration, there is a nozzle support 36 which can be rotated about a horizontal axis. There are two alternating nozzles on it, each alternating nozzle being assigned a beam channel arranged on the other side of the rotation axis, through which the laser beam crosses the nozzle support before it reaches the nozzle. Another design provides a disk-shaped nozzle support, which comprises a rotation axis extending parallel to the opticalaxis of the laser beam. The nozzle disk comprises merely two nozzles and rotates by means of an impact plate in which air is blown into a pressure space.
All these proposed solutions, however; are not satisfactory in use and require considerable equipment outlay for changing the nozzles with additional changer arms, as well as readjustment after each nozzle change.
It is therefore an object of the present invention to provide another way of changing the nozzle.